Harris Chisangano is a Zambian based philosopher, International researcher, educator and speaker
I like using science as an instrument to explain life and existence. I am a book writer and motivational speak
This paper centers on agriculture as a key to the sustenance of developing countries today
The challenge of addressing poverty probably remains the most vexing issue facing humankind today. While some successes have been noted in respect of the attainment of the Millennium Development Goals (MDGs), the most recent United Nations report on the MDGs however argues that ‘greater effort is required’ (UN, 2008, 4), especially with regards to issues such as addressing poverty in Africa and acting counter malnutrition
Within the context of multiple livelihood strategies, which the poor employ in the Global South, urban agriculture (UA) has received increasing recognition as an approach that can contribute to human survival, income and efforts to improve the overall quality of life (Sanyal, 1987; Thaman, 1975, 1995; UNDP, 1996; Mougeot, 1997; 2006). Gogwana (2001: 58) notes that UA is an “important socio-economic activity, particularly for the poor.”
In spite of the importance of urban agriculture to urban households, the activity is challenged by many factors, especially physical, social, political, institutional, and if moreover lacks legal frameworks (Hampwaye, 2008). Other constraints include those relating to post-production, the lack of technical assistance and the absence of associations in compared ISON with rural counterparts (UNDP, 1996; Vanderschueren et al., 1996).
While acknowledging that UA can only be regarded as one aspect of a multifaceted approach, UA, it is argued, deserves greater institutional recognition and support because of the role that it can potentially play in helping to address concerns of urban poverty and food insecurity. At the same time, decentralization in both South Africa and Zambia has resulted in a larger degree of local decision-making powers.
Abstract: Perovskite, CaTiO3, is the prototype of an extensive group of materials. They are capable of considerable chemical modification, with the further capability of undergoing structural modification by the intercalation of thin sheets of intrusive materials (both inorganic and organic) between the cubic perovskite layers, to form a range of "layered" perovskites. These changes bring about alterations in their electronic, structural, and other properties, permitting some "tuning" toward specific ends. This paper collects the limited known thermodynamic data for layered perovskites of various chemical compositions and demonstrates by example that the thermodynamic layer values are substantially additive. This additivity may be exploited by summing properties of the constituent oxides, by adding differences between adjacent compositions within a series, or even by substitution of oxides for one another, thus permitting prediction beyond the known range of compositions. Strict additivity implies full reversibility so that the additive product may be unstable and may undergo structural changes, producing materials with new and potentially useful properties such as ferroelectricity, polarity, giant magnetoresistance, and superconductivity.
Pub.: 25 Jul '17, Pinned: 13 Oct '17
Abstract: The electronic structures of 35 A(2+)B(4+)O3 ternary cubic perovskite oxides, including their hypothetical chemical compositions, were calculated by a hybrid functional method with the expectation that peculiar electronic structures and unique carrier transport properties suitable for semiconductor applications would be hidden in high-symmetry cubic perovskite oxides. We found unique electronic structures of Si-based oxides (A = Mg, Ca, Sr, and Ba, and B = Si). In particular, the unreported cubic BaSiO3 has a very narrow band gap (4.1 eV) compared with conventional nontransition-metal silicates (e.g., ∼9 eV for SiO2 and the calculated value of 7.3 eV for orthorhombic BaSiO3) and a small electron effective mass (0.3m0, where m0 is the free electron rest mass). The narrow band gap is ascribed to the nonbonding state of Si 3s and the weakened Madelung potential. The existence of the predicted cubic perovskite structure of BaSiO3 was experimentally verified by applying a high pressure of 141 GPa. The present finding indicates that it could be possible to develop a new transparent oxide semiconductor of earth abundant silicates if the symmetry of its crystal structure is appropriately chosen. Cubic BaSiO3 is a candidate for high-performance oxide semiconductors if this phase can be stabilized at room temperature and ambient pressure.
Pub.: 17 Aug '17, Pinned: 13 Oct '17